/**
 * Copyright (C) 2013 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.logging.Logger;

/**
 * Contains flags for Guice.
 */
public class InternalFlags {
    private static final Logger logger = Logger.getLogger(InternalFlags.class.getName());

    private static final IncludeStackTraceOption INCLUDE_STACK_TRACES = parseIncludeStackTraceOption();

    private static final CustomClassLoadingOption CUSTOM_CLASS_LOADING = parseCustomClassLoadingOption();

    private static final NullableProvidesOption NULLABLE_PROVIDES = parseNullableProvidesOption(NullableProvidesOption.ERROR);

    /**
     * The options for Guice stack trace collection.
     */
    public enum IncludeStackTraceOption {
        /** No stack trace collection */
        OFF,
        /**  Minimum stack trace collection (Default) */
        ONLY_FOR_DECLARING_SOURCE,
        /** Full stack trace for everything */
        COMPLETE
    }

    /**
     * The options for Guice custom class loading.
     */
    public enum CustomClassLoadingOption {
        /** No custom class loading */
        OFF,
        /** Automatically bridge between class loaders (Default) */
        BRIDGE
    }

    public enum NullableProvidesOption {
        /** Ignore null parameters to @Provides methods. */
        IGNORE,
        /** Warn if null parameters are passed to non-@Nullable parameters of provides methods. */
        WARN,
        /** Error if null parameters are passed to non-@Nullable parameters of provides parameters */
        ERROR
    }

    public static IncludeStackTraceOption getIncludeStackTraceOption() {
        return INCLUDE_STACK_TRACES;
    }

    public static CustomClassLoadingOption getCustomClassLoadingOption() {
        return CUSTOM_CLASS_LOADING;
    }

    public static NullableProvidesOption getNullableProvidesOption() {
        return NULLABLE_PROVIDES;
    }

    private static IncludeStackTraceOption parseIncludeStackTraceOption() {
        return getSystemOption("guice_include_stack_traces", IncludeStackTraceOption.ONLY_FOR_DECLARING_SOURCE);
    }

    private static CustomClassLoadingOption parseCustomClassLoadingOption() {
        return getSystemOption("guice_custom_class_loading", CustomClassLoadingOption.BRIDGE, CustomClassLoadingOption.OFF);
    }

    private static NullableProvidesOption parseNullableProvidesOption(NullableProvidesOption defaultValue) {
        return getSystemOption("guice_check_nullable_provides_params", defaultValue);
    }

    /**
     * Gets the system option indicated by the specified key; runs as a privileged action.
     *
     * @param name of the system option
     * @param defaultValue if the option is not set
     *
     * @return value of the option, defaultValue if not set
     */
    private static <T extends Enum<T>> T getSystemOption(final String name, T defaultValue) {
        return getSystemOption(name, defaultValue, defaultValue);
    }

    /**
     * Gets the system option indicated by the specified key; runs as a privileged action.
     *
     * @param name of the system option
     * @param defaultValue if the option is not set
     * @param secureValue if the security manager disallows access to the option
     *
     * @return value of the option, defaultValue if not set, secureValue if no access
     */
    private static <T extends Enum<T>> T getSystemOption(final String name, T defaultValue, T secureValue) {
        Class<T> enumType = defaultValue.getDeclaringClass();
        String value = null;
        try {
            value = AccessController.doPrivileged(new PrivilegedAction<String>() {
                public String run() {
                    return System.getProperty(name);
                }
            });
            return (value != null && value.length() > 0) ? Enum.valueOf(enumType, value) : defaultValue;
        } catch (SecurityException e) {
            return secureValue;
        } catch (IllegalArgumentException e) {
            logger.warning(value + " is not a valid flag value for " + name + ". " + " Values must be one of " + Arrays.asList(enumType.getEnumConstants()));
            return defaultValue;
        }
    }
}
